contact allergies

Question
i have a boston terrier,who is now 1yr old. since she was about 6 months old she gets a skin rash on her belly when she goes outside. i took her to the vet when this started,he gives her a shot which helps for about 2-4 weeks then it starts all over again. she itches and scrathes herself raw. i also have been giving her antihistamines,25mg three times a day. this does not seem to be helping. i have changed her food,i have tried an itch spray,i even tried a skin and coat vitamin,even the special shampoo. nothing seems to help her. so i decided to get on the internet and see what i could find out. this is how i found you. i found a site called petplace.com,which had some information about contact allergies for pets. this sounds like what my pet has. it also says antihistamines and vitamins do not work for contact allergies.is this true? i guess my real question is what can i do now to help her(sophie)with this problem? i would really like any info you could give me. it seems to be maybe the grass or something outside that trigers this.

Answer
If she has grass allergies, then walking the dog off of the grass may help.  I have several clients that use a large piece of indoor/outdoor carpeting in their yard to allow their dogs to eliminate.  Wiping the belly when she comes in from outside with a warm washcloth may remove any irritants. Also, if the shot helped, ask your vet for some cortisone tablets to keep the anti-inflamatory effect going.